The effects of conservation agriculture on crop
performance, soil quality and potential c emission
reduction and c sequestration in contrasting
environments in Mexico
Bram Govaerts, Ken Sayre, Nele Verhulst, Luc Dendooven
Agustin Limon-Ortega Leonardo Patiño-Zúñiga
Conservation Agriculture
 Comprises three basic components

Surface crop residue retention

Minimal soil movement

Crop rotation
Conventional agriculture
Sustainable agriculture
Crop rotation
Intensity of soil disturbance
Conventional
Adapted from Pereira
Surface crop retention
Minimum
Tillage
Direct
seeding
Conservation Agriculture is a
complex technology: it involves a
complete change in the
agricultural system.
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
Mexico
City
Toluca
2640 m
El Batán*
2249 m
Agua Fría
60 m
Tlaltizapá
n
940 m
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
Mexico
City
Toluca
2640 m
El Batán*
2249 m
Agua Fría
60 m
Tlaltizapá
n
940 m
Precipitation and pET (mm)
Climate
200
150
100
50
0
Month 1
2
3
4
Precipitation (mm)
5
6
7
8
9
10
11
12
LGP
pET (mm)
pET/2 (mm)
Soil Classification
Rastra
Ap
Arado
Ap0’
Cumulic
Phaeozem
A
Fine, mixed,
thermic Cumulic
Haplustoll
2Bw
2C
Characteristics
 Non-equatorial semi-arid
subtropical highlands
(2240 masl)
DROUGHT
 Periodical drought
 Periodical water excess
 Wind and water erosion
 Rain fed agriculture
 Grain yield < 3 ton ha-1
EROSION
Experimental Fields
Treatments
ZT
CT
K
R
MM
MM
MW
MW
WM
WM
WW
WW
P
PB
K
R
K
P
MM
MM
MW
MW
MW
MW
MW
WM
WM
WM
WM
WM
WW
WW
K = Keep residue on the field; R = Remove the residue ; P = Partial residue
retention
W = Wheat; M = Maize; B= Beans
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
El Batán*
2249 m
Mexico
City
Toluca
2640 m
Agua Fría
60 m
Tlaltizapá
n
940 m
Características del Valle del Yaqui
 27.33oN; 109.09oW
 38 m asl
 T(max) 26.7oC; T(min) 8.7oC
 Wheat growing season: November-May
 Maize – Sorghum: June - October
Soil – Station Obregon, Sonora, México
 Suelo – Vertisol
 Calcareous Vertisols (mixed montmorillonitic typic
Calciorthid)
 Low organic matter: 0.95 % (0-30 cm)
 Slightly alkaline: PH (CaCl2) = 7.7
 E.C. 0.8-1.9 dS m-1 (30-90 cm: 4.15 dS m-1)
%
Clay
Lime
Sand
0-30
43
24
33
30-60
48
25
27
Results: Yield
Towards a high and stable yielding system ?
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
Mexico
City
Toluca
2640 m
El Batán*
2249 m
Agua Fría
60 m
Tlaltizapá
n
940 m
Govaerts et al., 2005
Govaerts et al., 2005
Zero vs. Conventional
Govaerts et al., 2005
ZT
CT
ZT
CT
Yield results 1997-2005
Zero-tillage
Conventional tillage
Maize
Wheat
Maize
Wheat
Monoculture +
residue
4.3
5.3
3.5
4.9
Monoculture residue
2.2
4.4
3.4
4.3
Rotation + residue
5.1
5.4
4.2
4.9
Rotation - residue
4.0
3.4
3.8
4.4
Govaerts et al., 2005
Yield Stability
1.2
1.2
1.0
1
MM, ZT, K
0.8
MM, ZT, R
0.6
WM, ZT, K
0.4
WM, ZT, R
0.2
0.0
1990
WW, ZT, R
0.6
MW, ZT, K
0.4
MW, ZT, R
0.2
1995
2000
0
1990
2005
1995
2000
2005
1.2
1.2
1
1.0
MM, CT, K
0.8
MM, CT, R
0.6
WW, CT, K
WW, CT, R
0.8
0.6
MW, CT, K
WM, CT, K
0.4
WM, CT, R
0.2
0.0
1990
WW, ZT, K
0.8
0.4
MW, CT, R
0.2
1995
2000
2005
ZT = zero tillage, CT = conventional tillage
K = keep residue; R = remove residue
W = wheat; M = maize
0
1990
1995
2000
2005
Govaerts et al., 2005
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
El Batán*
2249 m
Mexico
City
Toluca
2640 m
Agua Fría
60 m
Tlaltizapá
n
940 m
Sayre et al., 2006
LSD for Rendimiento (0.05) = 563 kg/ha
7,500
7,500
7,190
6,950
7,000
6,500
8,000
6,356
7,000
6,500
6,225
6,000
6,000
5,500
5,500
4,985
5,000
5,000
4,500
4,500
3,978
4,000
4,000
3,500
3,500
3,000
3,000
Rendimiento de grano
(kg/ha)
Camas convencionales
Camas permanentes
Costos de producción
(MXN)
Ingresos (despues costos)
(MXN/ha)
Mexican pesos
Rendimiento de grano (kg/ha at 12% H2O)
8,000
Soil quality, not just a word
but a conceptual framework
Soil quality
 Variety of definitions
 Doran and Parkin (1994)
“it is the capacity of a soil to be functional, within
the limits imposed by the ecosystem and land
use, to preserve the biological productivity and
environmental quality, and promote plant, animal
and human health”
 Larson and Pierce (1994)
“fitness for use”
Selection Soil Parameters
 Limiting factor set: comparison of optimal
conditions for land use and field conditions
Ideal conditions for land use versus real
conditions
 Measuring possible critical indicators linked with
the limiting factors
 Multivariate analysis => most explicative
indicators = minimum dataset
(M)ANOVA
Indicators influenced by
• Residue
• Tillage
Chemical parameters 0-5
Chemical parameters 5-20
%C
%N
K
Mn
Zn
%C
Na
Mn
Biological parameters are weak!
Physical parameters Time-to-pond without plants
Time-to-pond with plants
% Macro aggregates
Permanent Wilting Point
Cone Penetration
Mean Weight Diameter
Probe Depth
Selected Parameters
Group
Chemical 0-5 Chemical 5-20
Indicator CEC
%C
%N
pH
P
Ca
Mg
K
Na
Fe
Mn
Zn
Cu
Ec
NH4+
NO3-
CEC
%C
%N
pH
P
Ca
Mg
K
Na
Fe
Mn
Zn
Cu
Ec
NH4+
NO3-
Physical
Biological
Small Ring Infiltration BTWC
Small Ring Infiltration IC
Time-to-pond without plants
Time-to-pond with plants
% Macro aggregates
% Meso aggregates
% Micro aggregates
Field capacity (0-5)
Field capacity (5-20)
Permanent Wilting Point (0-5)
Permanent Wilting Point (5-20)
Bulk density
Mean weight diameter
Cone penetration
Probe depth
PEN-7
PEN-17
PEN-27
MBB C
MBB N
PCA Soil physical properties
3
4
PC Top Soil Resistance
2
8
3
CP
1
7
2 %MA
14
0
6
-1
ZT, R
ZT, K
CT, R
CT, K
Loadings
13 1
5
16
12
15
PWP
TTPP
10
MWD
TTPWP
PR
11
9
-2
-3
-3
-2
-1
0
PC Soil Structure
Govaerts et al., 2006
1
2
3
PCA Soil chemical properties
3
4
8
2
Mn
PC 0-5 Mn
1
7
14
2
0
11
12
6
16
-1
10
Zn
%N
%C
5
15
9
K 1
0
1
ZT, R
ZT, K
3
13
CT, R
CT, K
Loadings
-2
-3
-3
-2
-1
PC 0-5 Nutrient Status
Govaerts et al., 2006
2
3
Aggregate stability
Total Soil
Wet sieving
Macroaggregates (M)
(>250 μm)
Microaggregates (m)
(53-250 μm)
Silt + Clay
(<53μm)
Microaggregate
isolator
Coarse POM-C + sand
(CPOM mM)
(>250 μm)
Micros within Macros
(mM)
Silt and clay (s+c mM)
(>53 μm)
(53-250 μm)
Density floatation +
dispersion
Inter-mMPOM-C
Intra-mMPOM-C
(53-250 μm)
(53-250 μm)
50
A
a
45
AB
40
B
35
b
30
25
20
15
A
a
10
5
AB
B
b
0
CTB + Res
PB + Res
Larga Macro-aggregates
Lichter et al., 2008
PB + Part
PB - Res
Small Macro-Aggregates
—————————————————————————————————————————
cPOM a
———————
Carbon
Treatment
Nitrogen
Microaggregates
within
macroaggregates
Silt and cay fraction
of
macroaggregates
———————
————————
Carbon
Nitrogen
Carbon
Nitrogen
————————————— (mg kg-1) ——————————
Tillage b
PB K
18.56 A
1.97 A
19.35 A
2.10 A
13.82 A
1.70 A
CB I
8.56 B
1.05 B
15.25 B
1.75 B
11.87 A
1.49 A
Residue management
c
PB K
18.56 A
1.87 A
19.35 A
2.09 A
13.82 A
1.70 A
PB P
9.83 B
1.20 B
17.11 A
1.91 A
14.29 A
1.66 A
PB R
8.61 B
1.29 B
16.05 A
1.86 A
14.19 A
1.72 A
—————————————————————————————————————————
Lichter et al., 2008
CO2 flux
CO2 flux (g CO2 m-² h-¹)
0.8
0.7
0.6
MW, CT, K
0.5
MW, ZT, K
0.4
WM, CT, K
0.3
WM, ZT, K
0.2
0.1
0
1
Residues Management
Tillage
Patiño-Zúñiga et al., 2008
CIMMYT in Mexico
Mexicali
22 m
Cd. Obregón
39 m
El Batán*
2249 m
Mexico
City
Toluca
2640 m
Agua Fría
60 m
Tlaltizapá
n
940 m
Tillage/Residue
Management
%
Organic
Matter
Conventional Till
Beds
Incorporated Residue
1.23
Permanent Beds
Burn Residue
1.32
Permanent Beds
Partial Removal
Residue
Na
Aggregate
Aggregate
Ppm Distribution Stability
MWD
MWD
SMB C
564
mg kg
SMB N
mg kg
soil-1
1.32
1.262
464
4.88
600
0.97
1.12
465
4.46
1.31
474
1.05
1.41
588
6.92
Permanent Beds
Retain Residue
1.43
448
1.24
1.96
600
9.06
Mean
1.32
513
1.15
1.434
552
6.40
LSD (P=0.05)
0.15
53
0.22
0.33
133
1.60
soil-1
Implementation of conservation
agriculture through a network
of hubs
The hub concept
 benchmark sites for research on the impacts of
CA
 focal point for regional (agro-ecological) capacitybuilding and scaling out of research and
innovation systems
 regional CA networks are established to facilitate
and foment research and extension of CA
innovation systems and technologies
 example of the functionality of CA systems
 structure to work together with partners including
farmers
 to test various best-bet technology options with farmers
 to integrate these options to improve farm level
economics and family well-being
 to provide a demonstration platform to extend these
technologies to surrounding farmers
 to provide a training/demonstration platform to bring
together all actors from other areas with similar
production systems and conditions
 to provide a platform to do relevant research
Strategic research feeding into the international network of hubs
Literature review
 Govaerts et al., submitted
 West and Post (2002), Jarecki and Lal (2003),
VandenBygaart et al. (2003), Blanco-Canqui and
Lal (2008) + Literature search (Web of Science)
 Only >5y and minimum 30cm
 Very little research in Africa, Central- LatinAmerica, Asia
Literature review
 Conventional till  Zero tillage
 8/62 cases C stock decreased
 21/62 cases C stock not significant different
 33/62 case C stock increased
 Increased rotation
 22/55 cases C stock decreased
 5/55 cases C stock not significant different
 28/55 cases C stock increased
Conclusions
 Not always increase in C stock
 Why? Not clear
 Underlying processes seem not fully understood
 Need for an international network of hubs linked
to strategic research sites
 Even if CA does not lead always to C stock
increase it is still the best practice to promote
Thanks
b.govaerts@cgiar.org